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react/packages/react-events/docs/Press.md
2019-04-26 08:11:40 +01:00

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Press

The Press module responds to press events on the element it wraps. Press events are dispatched for mouse, pen, touch, and keyboard pointer types. Press events are only dispatched for keyboards when pressing the Enter or Spacebar keys. If neither onPress nor onLongPress are called, this signifies that the press ended outside of the element hit bounds (i.e., the user aborted the press).

Press events do not propagate between Press event responders.

// Example
const Button = (props) => (
  const [ pressed, setPressed ] = useState(false);
  return (
    <Press
      onPress={props.onPress}
      onPressChange={setPressed}
      onLongPress={props.onLongPress}
    >
      <div
        {...props}
        role="button"
        tabIndex={0}
        style={
          ...buttonStyles,
          ...(pressed && pressedStyles)
        }}
      />
    </Press>
  );
);
// Types
type PressEvent = {
  pointerType: 'mouse' | 'touch' | 'pen' | 'keyboard',
  target: Element,
  type: 'press' | 'pressstart' | 'pressend' | 'presschange' | 'pressmove' | 'longpress' | 'longpresschange'
}

type PressOffset = {
  top: number,
  right: number,
  bottom: number,
  right: number
};

delayLongPress: number = 500ms

The duration of a press before onLongPress and onLongPressChange are called.

delayPressEnd: number

The duration of the delay between when the press ends and when onPressEnd is called.

delayPressStart: number

The duration of a delay between when the press starts and when onPressStart is called. This delay is cut short (and onPressStart is called) if the press is released before the threshold is exceeded.

disabled: boolean

Disables all Press events.

onLongPress: (e: PressEvent) => void

Called once the element has been pressed for the length of delayLongPress. If the press point moves more than 10px onLongPress is cancelled.

onLongPressChange: boolean => void

Called when the element changes long-press state.

onLongPressShouldCancelPress: () => boolean

Determines whether calling onPress should be cancelled if onLongPress or onLongPressChange have already been called. Default is false.

onPress: (e: PressEvent) => void

Called immediately after a press is released, unless either 1) the press is released outside the hit bounds of the element (accounting for pressRetentionOffset and TouchHitTarget), or 2) the press was a long press, and onLongPress or onLongPressChange props are provided, and onLongPressCancelsPress() is true.

onPressChange: boolean => void

Called when the element changes press state (i.e., after onPressStart and onPressEnd).

onPressEnd: (e: PressEvent) => void

Called once the element is no longer pressed (because it was released, or moved beyond the hit bounds). If the press starts again before the delayPressEnd threshold is exceeded then the delay is reset to prevent onPressEnd being called during a press.

onPressMove: (e: PressEvent) => void

Called when a press moves within the hit bounds of the element. onPressMove is called immediately and doesn't wait for delayed onPressStart. Never called for keyboard-initiated press events.

onPressStart: (e: PressEvent) => void

Called once the element is pressed down. If the press is released before the delayPressStart threshold is exceeded then the delay is cut short and onPressStart is called immediately.

pressRetentionOffset: PressOffset

Defines how far the pointer (while held down) may move outside the bounds of the element before it is deactivated. Ensure you pass in a constant to reduce memory allocations.

preventDefault: boolean = true

Whether to preventDefault() native events. Native behavior is prevented by default. If an anchor is the child of Press, internal and external navigation should be performed in onPress/onLongPress. To rely on native behavior instead, set preventDefault to false, but be aware that native behavior will take place immediately after interaction without respect for delays or long press.